CC Search - Search for Creative Commons-licensed media including images, music and movies
FreeRangeStock provides free stock images -- free membership required.
Morguefile.com - includes free, Creative-Commons-licensed photos and paid photos.
Perry-Castañeda Library Map Collection -- Free map images
Realia Project - images from around the world, designed for use in language instruction. Non-commerical use only.
Search Flickr.com for Creative Commons-licensed images.